String Interview Questions

QUESTION-6 Copy String Manually Without Using strcpy().

Answer-

int main()
{
    char s1[100], s2[100], i;

    printf("Enter string s1: ");
    scanf("%s",s1);

    for(i = 0; s1[i] != '\0'; ++i)
    {
        s2[i] = s1[i];
    }

    s2[i] = '\0';
    printf("String s2: %s", s2);

    return 0;
}

QUESTION-7 Remove Characters in String Except Alphabets

Answer-

int main()
{
    char line[150];
    int i, j;
    printf("Enter a string: ");
    gets(line);

    for(i = 0; line[i] != '\0'; ++i)
    {
        while (!( (line[i] >= 'a' && line[i] <= 'z') || (line[i] >= 'A' && line[i] <= 'Z') || line[i] == '\0') )
        {
            for(j = i; line[j] != '\0'; ++j)
            {
                line[j] = line[j+1];
            }
            line[j] = '\0';
        }
    }
    printf("Output String: ");
    puts(line);
    return 0;
}

QUESTION-8 Check if a given String is Palindrome

Answer-

 
void main()
{
    char string[25], reverse_string[25] = {'\0'};
    int  i, length = 0, flag = 0;
 
    fflush(stdin);
    printf("Enter a string \n");
    gets(string);
    
    for (i = 0; string[i] != '\0'; i++)
    {
        length++;
    }
    for (i = length - 1; i >= 0; i--)
    {
       reverse_string[length - i - 1] = string[i];
    }
    

    for (i = 0; i < length; i++)
    {
        if (reverse_string[i] == string[i])
            flag = 1;
        else
            flag = 0;
    }
    if (flag == 1)
        printf("%s is a palindrome \n", string);
    else
        printf("%s is not a palindrome \n", string);
}

QUESTION-9 Replace Lowercase Characters by Uppercase & Vice-Versa

Answer-

 
void main()
{
    char sentence[100];
    int count, ch, i;
 
    printf("Enter a sentence \n");
    for (i = 0;(sentence[i] = getchar()) != '\n'; i++)
    {
        ;
    }
    sentence[i] = '\0';
    /*  shows the number of chars accepted in a sentence */
    count = i;
    printf("The given sentence is   : %s", sentence);
    printf("\n Case changed sentence is: ");
    for (i = 0; i < count; i++)
    {
        ch = islower(sentence[i])? toupper(sentence[i]) :
tolower(sentence[i]);
        putchar(ch);
    }
}

QUESTION-10 Remove given Word from a String

Answer-

 
void main()
{
    int i, j = 0, k = 0, count = 0;
    char str[100], key[20];
    char str1[10][20];
 
    printf("enter string:");
    scanf("%[^\n]s",str);
 
    for (i = 0; str[i]!= '\0'; i++)
    {
        if (str[i]==' ')
        {
            str1[k][j] = '\0';
            k++;
            j = 0;
        }
        else
        {
            str1[k][j] = str[i];
            j++;
        }
    }
    str1[k][j] = '\0';
    printf("enter key:");
    scanf("%s", key);
    
    for (i = 0;i < k + 1; i++)
    {
        if (strcmp(str1[i], key) == 0)
        {
            for (j = i; j < k + 1; j++)
            strcpy(str1[j], str1[j + 1]);
            k--;
        }
 
    }
    for (i = 0;i < k + 1; i++)
    {
        printf("%s ", str1[i]);
    }
}
}